It is often desired to remove water or heavy organic droplets from a natural gas stream, from synthesis gas for ammonia, etc., or the removal of water and organics from an inert gas in a gas liquefaction plant in order to avoid contamination of equipment and pipelines. In some instances, a small amount of entrained liquid can be tolerated and in others these gases need to be "dry". A variety of apparatus and methods have been developed to accomplish this result.
Gravitational phase separators have long been used to remove liquid droplets from a gas stream and they simply rely on gravity and reduced gas velocity to accomplish the separation. In a gravitational phase separator, typically a column, the velocity of the gas as it is passed through the unit is reduced to permit the droplets to coalesce and settle out by the action of gravity. The liquid then is drained from the bottom of the phase separator and the gas is discharged from the top.